Use of the iterative diagnosis and design approach in the development of suitable agroforestry systems for a target area

The process of iterative diagnosis and design with the active participation of farmers and extension agents was found effective in identifying appropriate agroforestry systems for farmers in the Bugesera and Gisaka-Migongo (BGM) regions of Rwanda. Periodic re-evaluation of research assumptions and technology designs was based on feedback from farmers and extentionists through regular visits to station trials, early initiation of on-farm testing, and interaction with farmer cooperators through informal discussions and formal surveys focused on specific agroforestry technologies. Statistical analysis is valuable for comparison between regions or periods. However, valid conclusions can be drawn without statistics, by employing several farmer-participatory approaches and pooling and properly interpreting the data obtained from them. Farmers' preferred uses of tree biomass in the BGM regions and appropriate agroforestry systems are discussed. If researchers and development agents do not consider the farmers' real needs, circumstances, available resources and management capacity with regard to tree planting, they will fail in identifying and extending suitable agroforestry systems for any region. This study was a part of the ISAR/IITA/World Bank FSR Project, implemented in the BGM regions of Rwanda during 1983–1988.     

Structure and function of traditional agroforestry systems in the western Himalaya. II. Nutrient cycling

Budget of nutrient in plant and soil, and their rates of recycling in three types of traditional agroforestry systems in mid elevations of the western Himalaya were studied. Concentration of nitrogen and potassium was significantly higher in fruits and leaves than in branches, boles, and litter. Grewia optiva, an important fodder tree, was found to be rich in potassium, vegetable crops in nitrogen, and weeds in phosphorus. Maximum store of nutrients was estimated in aboveground biomass of agrihortisilvicultural system: nitrogen 532, phosphorus 40, potassium 461, calcium 400, and magnesium 298 kg/ha; it was closely followed by that in agrihorticultural system, and both these had sbout 2-fold higher nutrient stock as compared to agrisilvicultural system. In the case of the former two systems, considerable quantity of nutrients up to nitrogen 169, phosphorus 14, potassium 165, calcium 97, and magnesium 65 kg/ha, for example in agrihortisilvicultural system, was recycled through debris of crops and weeds, and tree leaf litter, while the recycling rate was almost half in agrisilvicultural system. Through ‘harvest’ potassium was depleted in the largest quantity from the system, followed by nitrogen, magnesium, calcium, and phosphorus; much higher loss occurred through agricultural and/or horticultural edible parts as compared to fuel and fodder biomass. For example, the loss through agricultural crops and horticultural fruits for nitrogen in agrihortisilvicultural system was up to 75 percent and 38 percent respectively of the total annual uptake. This heavy loss makes the system unstable from a nutrient point of view particularly for nitrogen and potassium until external inputs are added through organic and inorganic fertilizers. Agrihortisilvicultural system is remarkably efficient in view of biomass productivity for fuel, fodder and fruits, and also from nutrient point of view provided losses through harvest are compensated externally.     

Comparative productivity of Prosopis cineraria and Tecomella undulata based agroforestry systems in degraded lands of Indian Desert

Tree-crop interactions were monitored by measuring tree growth characters of Prosopis cineraria L.and Tecomella undulata L.and yields of Vigna radiata(L) in agroforestry systems in degraded lands of Indian Desert.Potential competition for resource between the trees and associated crop was analyzed by measuring soil water contents, soil organic matters and NH4-N at different depths of soil layers i.e., 0-25 cm, 25-50 cm and 50-75 cm in the experimental plots.The plots size were 16 m × 18 m(D1), 20 m × 18 m(D...     

An evaluation of agroforestry systems as a rural development option for the Brazilian Amazon

In the Brazilian Amazon mass deforestation has resulted from a sequenceof road building, extractive logging, and pasture development during the pastthree decades. Ranchers have consolidated small agricultural holdings, pushingfarmers to move to forest frontiers or urban fringes, prompting furtherdeforestation and social instability. In response to this conversion ofAmazonian forests, the authors sought to identify both economically viable andmore sustainable development alternatives within the Brazilian state ofPará. There, local farmers of Japanese descent have developed a varietyof agroforestry systems in which 10 to 20 hectare (ha) fields yieldincomes comparable to 400 to 1,200 ha pastures. In addition, suchcrop fields generate substantially more rural employment per hathan do pastures. Ongoing forest conversion to pasture is clearly not a productof sound economic decision making. Improved land zoning and public policiescould favor agroforestry over further pasture expansion, stabilizing ruralpopulations while helping to conserve the Amazon's remaining forests. This revised version was published online in June 2006 with corrections to the Cover Date.     

Transfer of salt and nutrients in Bruguiera gymnorrhiza leaves during development and senescence

The life span of leaves in Bruguiera gymnorrhiza, non-secretor of salt, can be divided into a leaf developing stage, a leaf functioning stage and a leaf senescing stage. The concentrations (mg/g) and the contents (mg/leaf) of Na and Cl increased at the leaf developing stage and remained almost constant at the leaf functioning stage. At the leaf senescing stage, the concentrations of Na and Cl increased markedly by 45 and 31% respectively, while their contents only increased by 16 and 4% respectively. The K/Na ratio remained constant at the leaf functioning stage, and decreased at the leaf senescing stage. During leaf senescence, there was a marked decline in leaf mass (20%) and in leaf area (15%). During senescence, 60% of its N, 48% of its P and 46% of its K was transferred out of the senescing leaf.     

Approaches to modelling the uptake of water and nutrients in agroforestry systems

This review presents information about root systems of crops and trees and describes approaches that have been used to model uptake of water and nutrients in crops that may have application to agroforestry systems. Only a few measurements of the distribution of tree roots in agroforestry systems have been published and these are predominantly in alley cropping systems with young trees. Therefore, a major limitation to developing water and nutrient uptake models for trees is the lack of adequate measurements and conceptual models for describing the distribution of roots spatially and temporally. Most process-based modelling approaches to water and nutrient uptake integrate the activities of a single root over the whole root system. Several difficulties can be foreseen with applying these approaches to roots of older trees including the presence of mycorrhizal associations so that the root surface is not the site of uptake, the uncertainty as to whether all tree roots are active in taking up water and nutrients, and the fact that, unlike annual crops, trees have substantial reserves of nutrients that can be mobilised to support growth so that the notion of a plant demand regulating uptake may prove difficult to define. The review concludes that a programme of experimental measurements is required together with modelling using approaches both in which roots are implicit, and in which process-based models with roots allow competitive ability to be assessed.     

Linking on-station research with on-farm testing: The case of agroforestry and organic matter-based cropping systems for the Rwanda farming systems improvement project

Hillside farming with its attendant erosion and decline in soil fertility is common-place in the area served by the Farming Systems Improvement Project. The project is designing land-use systems that would check erosion, increase soil organic matter and restore soil fertility. These systems will allow small farmers to increase or maintain product long-term basis without resorting to the use of high doses of inorganic fertilizers which are not readily available in the country. The use of leguminous shrubs and cover crops as nutrient sources — concepts embodied in agroforestry and organic farming systems — are options that landuse experts think might solve the problem. However, there is a dearth of knowledge about the biological feasibility of these interventions in the project area. This paper reports how FSIP combined problem diagnosis and analysis, researcher-managed adaptive trials and a field day to attack this lack of information. The rationale for using this approach is to address farmers' real needs, save time and minimize risk to poor farmers. This article is a contribution from the University of Arkansas' USAID-supported Farming System Improvement Project (FSIP) in Rawanda (USAID 696-0110), B.P. 625, Kigali, Rawanda. Authors are the project's soil scientist/agronomist and its extension and training specialist respectively.     

Linking on-station research with on-farm testing: The case of agroforestry and organic matter-based cropping systems for the Rwanda farming systems improvement project

Hillside farming with its attendant erosion and decline in soil fertility is common-place in the area served by the Farming Systems Improvement Project. The project is designing land-use systems that would check erosion, increase soil organic matter and restore soil fertility. These systems will allow small farmers to increase or maintain product long-term basis without resorting to the use of high doses of inorganic fertilizers which are not readily available in the country. The use of leguminous shrubs and cover crops as nutrient sources — concepts embodied in agroforestry and organic farming systems — are options that landuse experts think might solve the problem. However, there is a dearth of knowledge about the biological feasibility of these interventions in the project area.This paper reports how FSIP combined problem diagnosis and analysis, researcher-managed adaptive trials and a field day to attack this lack of information. The rationale for using this approach is to address farmers' real needs, save time and minimize risk to poor farmers.This article is a contribution from the University of Arkansas' USAID-supported Farming System Improvement Project (FSIP) in Rawanda (USAID 696-0110), B.P. 625, Kigali, Rawanda. Authors are the project's soil scientist/agronomist and its extension and training specialist respectively.     

耐盐碱乔木在盐碱地环境中的应用概况

时滨城区盐碱土绿化乔木的应用状况进行了调查。结果表明：该地区有盐碱土绿化乔木17科,37种;现已广泛栽培应用21种,其中有24．32％能耐中度盐碱,部分种类只耐轻度盐碱,有1种为特耐盐植物;有野生及乡土耐盐碱乔木种类7种,其中2种为很有价值的盐碱土绿化乔木。     

Land classification for choice of tree species on farm lands in the Attock District of Punjab,Pakistan

In Pakistan, particularly in Punjab Province, it is difficult for agrofarmers to combine their indigenous knowledge and modern scientific methods to evaluate existing traditional farming systems and forestry practices. This requires an evaluation of indigenous soil classification in simple terms along with knowledge of the local flora, especially trees. This study focuses on land suitability classification for trees in the Attock District of Punjab, Pakistan. A survey was conducted which included interviews of local agrofarmers as well as standard soil analyses including both chemical and physical determinations of local soil types. An evalu- ation of soil types for cultivation of various crops was carried out given its total extent, component soil series and their proportions, spotting characteristics of each soil series and their major limitations/hazards for trees/crops. These would lead to the identification of various tree species according to soil characteristics. Then, according to the soil types and species, a land suitability map was obtained for the choice of tree species by using geographic information system (GIS) software. Land suitability classification will help local agroforesters/agrofarmers in matching suitable agricultural trees/crops properly for different soils in the area.     

Components of the water balance for tree species under evaluation for agroforestry to control salinity in the wheatbelt of Western Australia

The soil water balance technique was used to study evaporation from two fodder tree species, tenEucalyptus species and annual pasture over a three year period after planting in the Western Australian wheatbelt. Evaporation is the total water loss by the processes of transpiration, evaporation from the soil surface and evaporation of water intercepted by plant canopies.Evaporation from both fodder trees and from seven of theEucalyptus species was greater than from pasture for one or more of the study years. The maximum difference in evaporation between trees and pasture was 82, 84 and 70 mm in the first, second and third study years, respectively. Higher evaporation from trees was associated with greater depletions in soil water than occurred beneath pasture. Upward movement of water from wet soil beneath the root zone was found under trees, with a maximum flux of 30 mm observed over a one year period beneathE. camaldulensis.The water use efficiency of fodder trees was significantly higher than for mostEucalyptus species, due to greater yields from fodder trees. Biomass production was found to be a good indicator of the water use of eucalypts over the first two years of growth, but the relationship between productivity and water use was found to differ for species with tree and mallee forms. In the third year of study, obvious differences in the relation between water use and yield were observed for some species of eucalypts with high evaporation.     

An equation for the replacement value of agroforestry

This article examines some of the existing analytical tools which quantify both the ecological and economic aspects of intercropping decisions. The characteristics of tree crops are evaluated to determine how a specific tool, the replacement value of intercropping (RVI), could be modified to better interpret agroforestry improvements to bush fallow farming systems. The modified equation captures some of the potential production improvements associated with agroforestry by accounting for the fraction of time that a field is actually in production over the long run. The result is an improved estimate of the average annual difference between a tree/crop polyculture and a monoculture system which employs fallows.     

冬枣树盘土壤养分和盐分含量梯度分布研究

对离树干0~100cm半径的冬枣树盘表土层和20cm土层土壤养分和盐分含量进行了检测。结果表明:(1)表土层铵态氮含量先降后升,速效磷、速效钾含量先升后降;20cm土层铵态氮、速效磷含量先降后升,速效钾含量先升后降。(2)硫酸盐、氯化盐和重碳酸盐在表土层和20cm土层含量均表现先升后降的趋势。     

Design and development of agroforestry systems for Illinois,USA: silvicultural and economic considerations

Recommended managerial inputs and associated outputs expected from practicing agroforestry on marginal farm lands in the central USA are discussed. Modeled management combinations are based on five timber species, three sites indices, three timber growth rates, five agricultural crops, all common crop rotations, and three tillage systems. Black walnut (Juglans nigra L.), combined with row crop production, is used to illustrate a specific multicropping alternative. Based on net present value, modeled agroforestry systems incorporating black walnut performed better on the better sites and at the medium to high timber growth rates whereas management systems using red oak (Quercus rubra L.) with row crops performed better on the poorer sites and at the lower growth rates. For agroforestry to be competitive with traditional agriculture, medium to high timber growth rates were necessary. Also, lower interest rates and the existing U.S. income tax structure favored agroforestry versus traditional agriculture. Substantial increases in net income may be possible through incorporating other income producing activities such as nut production within the agroforestry system.     

An economic analysis of improved agroforestry practices in the Amazon lowlands of Ecuador

Since 1985, Ecuador's Ministry of Agriculture has undertaken a demonstration project to promote improved agroforestry practices in already cleared lands of Ecuador's Amazon lowlands to promote regeneration of deforested areas. An important expected outcome of this project is to ameliorate growing population pressures on remaining national forests and natural reserves. These practices include managing natural regeneration of marketable timber trees intercropped to Coffea canephora var. robusta and grass-legume associations, using adequate techniques of coffee pruning, and planting Desmodium ovalifolium CIAT 350 as a ground cover crop or a forage legume in paddocks of the genus Brachiaria. This research was conducted to assess the potential economic impact of such a strategy and to feed back information on research and policy issues.Improved agroforestry practices in this region are not only technically practicable but also economically feasible. Proposed technologies enhance long-term productivity of both land and labor while saving on external inputs and hired labor, making on-going systems more adoptable and sustainable. Future land-use policies should consider on-farm primary forest preservation and controlled natural regeneration of high-value timber in secondary forests as socially efficient land-use patterns. Future research must address germplasm of grass and forage legumes both shade tolerant, and less field management-demanding than current ones.To have a lasting effect this technology should probably be incorporated into a Regional Forest Management Plan, for sustainable production at the secondary forests created with agroforestry technology.in cooperation with Fundación para el Desarrollo Agropecuario del Ecuador, FUNDAGRO, Casilla No. 219, Suc. 16 CEQ, Quito, Ecuador     

Survival,growth and productivity of tree species under evaluation for agroforestry to control salinity in the Western Australian wheatbelt

Survival and growth were investigated for 10Eucalyptus species and 2 fodder tree species planted for salinity control in the wheatbelt of Western Australia. After two years of growth the trees were harvested to determine fodder biomass production and yields of cineole from the eucalyptus leaf oil. Subsequent harvests were conducted at three and five years after planting.At each harvest, biomass production from fodder species was greater than from most species of eucalypts. Biomass yields from eucalypts were variable, and there were no consistent trends in the productivity of the different species for the three harvests.Leaf cineole concentrations and cineole yields were low after two years of growth, but after three and five years cineole yields were generally higher from all species.E. kochii subspp.plenissima andkochii, E. horistes, E. radiata andE. angustissima produced consistently high cineole yields after three and five years. These species appear to have potential for the production of high grade eucalyptus oil in the wheatbelt of Western Australia.     

桉树人工林地土壤酶活性与营养元素含量关系研究

运用典范相关分析 (canonicalcorrelationanalysis)对桉树人工林地土壤酶活性和土壤营养元素含量关系的研究表明 ,土壤过氧化氢酶、脲酶和蛋白酶活性与营养元素全P和全N含量关系最大 ,即正效应较大 ,它们对N、P的转化具有重要作用。转化酶活性在一定程度上对土壤养分K、P和Mg含量有一定的负相关作用。“综合土壤酶因子”可作为土壤肥力评价的一个指标     

The potential of agroforestry to increase primary production in the Sahelian and Sudanian zones of West Africa

The article presents a critical evaluation of agroforestry systems as regards their potential to increase primary production in the Sahelian and Sudanian zones of West Africa. The suggestion that trees would always and everywhere be profitable for the region will be counterproductive, the basis for disappointments and a waste of money. One has to consider carefully which properties of woody species could serve which objective, where and under what circumstances.Primary production is limited by water availability in the north Sahelian zone only, elsewhere in the region nutrient availability is critical. Woody species influence the water balance via rainfall interception, the influence on evapotranspiration and the influence on water infiltration. The ultimate result for grasslands and crops depends upon local conditions; positive effects of windbreaks should be particularly attributed to protection against mechanical stress. Processes that influence nutrient availability under trees are those acting via redistribution, those reducing nutrient losses and those increasing soil fertility. Of the latter processes, serious limitations exist in the region concerned: nitrogen fixation is limited by phosphorus shortage mainly and deep rooting is very limited and so is possible uptake of minerals from deep soil layers.The positive influence from woody species on soil fertility and primary production varies with average annual rainfall and soil type; its importance increases more than proportionally with rainfall going south. This positive influence is basically linked to the redistribution of nutrients and water, the internal nutrient cycling and the related enlarged plant-litter-soil nutrient cycle. Taking advantage of its effects is difficult and risks further depletion of soil fertility. Moreover, since woody species generally compete with the herb layer, it will be difficult to develop agroforestry in such a way that the positive influences are not overridden by negative ones. The potential to increase nutrient availability by agroforestry systems is limited and windbreaks are more beneficial under conditions which are rare in the region.More research is needed to determine under which conditions introduction of woody species may be beneficial.

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Le potentiel de l'agroforesterie pour augmenter la production primaire dans les zones sahélienne et soudanienne de l'Afrique de l'Quest

Résúme Une évaluation critique de l'agroforesterie est présentée, en ce qui concerne la possibilité d'augmenter la production primaire dans les zones sahélienne et soudanienne de l'Afrique de l'Quest. La supposition que dans cette région des arbres seraient toujours et partout avantageux, n'est pas productive, mais plutôt une cause de déceptions et un gaspillage de ressources. Il faut se demander quelles propriétés des espéces ligneuses pourraient servir quels objectifs, oú et sous quelles conditions.Seulement dans zoneone nord-sahélienne la production primaire est limitée par la disponibilité en eau; ailleurs c'est la disponsibilité des éléments nutritifs qui est la plus déterminante. Des espéces ligneuses influencent le bilan d'eau par l'interception de la pluie, par des modifications de l'evapotranspiration, et par une amélioration de l'infiltration d'eau. La conséquence pour les pâturages et les cultures dépend des conditions locales; les avantages de brise-vents dépendront notamment de la protection contre le stress mécanique. Des processus influençant la disponibilité des éléments nutritifs souls les arbres sont ceux agissant par la redistribution, par la diminution des pertes et par l'augmentation de la fertilité. Les derniers processus ont des limitations sérieuses dans la zone: la fixation d'azote est surtout limitée par le manque de phosphore et l'enracinemment profond paraît limité et ainsi la possibilité de profiter d'une disponibilité éventuelle de minéraux en profondeur.L'influence positive des espéces ligneuses sur la fertilité du sol et la production primaire varie avec la pluviosité annuelle et le type de sol; son importance accroît plus que proportionnelle avec la pluviosité vers le sud. Cet influence positive est liée à la redistribution des éléments nutritifs et de l'eau, au recyclage interne des éléments nutritifs et le cycle agrandi y en être la conséquence, de ces éléments en plante-litière-sol. Pour profiter de ses effets est difficile et on risque l'épuisement supplémentaire des éléments nutritifs. En plus, suite à la concurrence entre les espéces ligneuses et la strate herbacée, c'est difficile à développer l'agroforesterie d'une telle façon que les avantages ne seront pas surpassés par les inconvéniences. Des brise-vents sont avantageux sous des conditions qui sont rares dans la zone.Plus de recherche est nécessaire pour déterminer les conditions sous lesquelles l'introduction des espéces ligneuses peut être profitable.

     

Carbon storage of artificial forests in rehabilitated lands in the upper reaches of the Yellow River

We studied 10-to 27-year-old artificial forests on rehabilitated lands in the upper reaches of the Yellow River with the objective of comparing the carbon densities of various artificial and natural forests. Under artificial plantations, the vegetation layer (including roots) had a mean carbon density of 111.3 t/hm², the litter layer a density of 5.1 t/hm², and the soil layer a density of 64.9 t/hm². These values accounted for 28.6%, 13.8%, and 61.0% of their respective counterparts in the natural secondary forests under the same site conditions in the region. The ratios of carbon density among vegetation, litter, and soil pools were 39.6:1.8:58.6 for artificial forests and 57.4:2.7:39.9 for natural forests. The carbon densities of the vegetation and litter layers increased exponentially with forest age. The total carbon density ratios were also increasing gradually. Although the mean total carbon density of the artificial forests in the rehabilitated lands was 281.2 t/hm² in the experimental area, it accounted for only 41.5% of the carbon density of the natural secondary forests (677.4 t/hm²). The annual increase in total carbon density of artificial forests was as high as 15.2 t/hm², which was 11.7% more than that of natural forests and 6.8 times higher than that (1.95 t/hm) of artificial forests in the entire country as measured during 1994–1998. This indicates that growth and carbon storage capacity of artificial forests in the rehabilitated lands were higher than those of forests on the barren hills and the secondary forests. We concluded that the conversion project from croplands to forests and grasslands based on scientific principles is very important in the formation of carbon sinks for reducing greenhouse effects. __________ Translated from Journal of Beijing Forestry University, 2005, 27(6): 1–8 [译自: 北京林业大学学报, 2005, 27(6): 1–8]     

杉木幼林地水土流失动态研究

杉木幼林地水土流失动态研究＊何贵平陈益泰蔡宏明封剑文关志山关键词杉木、幼林地、水土—养分流失、预测模型杉木（Ｃｕｎｎｉｎｇｈａｍｉａｌａｎｃｅｏｌａｔａ（Ｌａｍｂ．）Ｈｏｏｋ）是我国南方的主要用材树种，常以营造纯林为主，整地方式又以全垦挖大穴或火烧炼...